class Orocos::Avahi::NameService

Name service to access Orocos Tasks which are publishing their IOR via Avahi

Public Class Methods

new(searchdomain) click to toggle source

A new instance of NameService which is listening on the given search domain. The serach domain must have a ._tcp or ._udp at the end for a protocol type.

@param [String] searchdomain The search domain the name service is listening to (_myrobot._tcp / _myrobot._udp)

# File lib/orocos/name_service.rb, line 684
def initialize(searchdomain)

    raise ArgumentError,"no serachdomain is given" unless searchdomain

    @registered_tasks = Hash.new
    @searchdomain = searchdomain

    begin
        require 'servicediscovery'
        @avahi_nameserver = ::Avahi::ServiceDiscovery.new
    rescue LoadError
        raise LoadError, "NameService: 'distributed_nameserver' needs to be installed for Avahi nameservice support"
    end
    # Start listening on the given domains (this does refer to the _myservice._tcp service domain and not(!) the .local domain)
    begin
        @avahi_nameserver.listen_on(Array(@searchdomain))
    rescue RuntimeError
        raise ArgumentError, "given search domain #{searchdomain} is invalid. Use '_myservice._tcp'."
    end
end

Public Instance Methods

deregister(task) click to toggle source

Deregisters the given name or task from the name service.

@param [String,TaskContext] task The name or task @note This only works for tasks which were registered by the same ruby instance.

# File lib/orocos/name_service.rb, line 735
def deregister(task)
    name = if task.respond_to? :name
               task.name
           else
               task
           end
    @registered_tasks.delete name
end

get(name,options = Hash.new) click to toggle source

(see Orocos::NameServiceBase#get)

# File lib/orocos/name_service.rb, line 760
def get(name,options = Hash.new)
    options = Kernel.validate_options options,:name,:namespace,:process
    ns,_ = Namespace.split_name(name)
    options[:namespace] ||= ns
    Orocos::TaskContext.new(ior(name),options)
rescue Orocos::CORBA::ComError => e
    raise Orocos::NotFound, "task context #{name} is registered but cannot be reached."
end

ior(name) click to toggle source

(see Orocos::NameServiceBase#ior)

# File lib/orocos/name_service.rb, line 745
def ior(name)
    services = @avahi_nameserver.find_services(name)
    if services.empty?
        raise Orocos::NotFound, "Avahi nameservice could not find a task named '#{name}'"
    elsif services.size > 1
        warn "Avahi: '#{name}' found multiple times. Possibly due to publishing on IPv4 and IPv6, or on multiple interfaces -- picking first one in list"
    end
    ior = services.first.get_description("IOR")
    if !ior || ior.empty?
        raise Orocos::NotFound, "Avahi nameservice could not retrieve an ior for task #{name}"
    end
    ior
end

names() click to toggle source

(see Orocos::NameServiceBase#names)

# File lib/orocos/name_service.rb, line 706
def names
    @avahi_nameserver.get_all_services.uniq
end

Registers the IOR of the given {Orocos::TaskContext} on the Avahi name service

@param [Orocos::TaskContext] task The task. @param [String] name The name which is used to register the task.

# File lib/orocos/name_service.rb, line 718
def register(task,name=task.name)
    existing_service = @registered_tasks[name]
    service = existing_service || ::Avahi::ServiceDiscovery.new
    service.set_description("IOR",task.ior)
    if existing_service
        service.update
    else
        @registered_tasks[name] = service
        service.publish(name, @searchdomain)
    end
    service
end

same_namespace?(name) click to toggle source

# File lib/orocos/name_service.rb, line 710
def same_namespace?(name)
    true
end